首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   38篇
  完全免费   1篇
  林业   39篇
  2021年   1篇
  2014年   9篇
  2013年   2篇
  2012年   4篇
  2011年   1篇
  2010年   3篇
  2009年   2篇
  2008年   6篇
  2007年   2篇
  2006年   1篇
  2005年   2篇
  2004年   1篇
  2001年   1篇
  1999年   1篇
  1998年   1篇
  1997年   1篇
  1996年   1篇
排序方式: 共有39条查询结果,搜索用时 140 毫秒
1.
油茶优良无性系及其丰产栽培技术要点   总被引:6,自引:0,他引:6  
1油茶优良无性系特点及栽培意义油茶主要分布在中国南方的江西、湖南、广西、广东、福建等省、区。属亚热带植物。是重要的木本油料树种。茶油为南方部分省、区主要食用油之一。由于其含不饱和脂肪酸高达92%以上,超过世界著名的橄榄油的含量(89%),特别是富含人体必须但又不能自身合成的物质———亚油酸,对防止心血管疾病及婴幼儿发育成长有很大的促进作用,现已成为人们追求的高档保健食用油,被誉为“纯天然绿色食品”。已进入国际市场,价格达每公斤160元人民币,因此,发展经营好油茶具有十分重大的意义。自20世纪90年代以来,经林学专家潜心…  相似文献
2.
南方桉树人工林雨雪冰冻灾害调查分析   总被引:3,自引:3,他引:16  
2008年初,中国南方8省(区)桉树人工林遭受严重雨雪冰冻寒害.调查分析表明:桉树人工林受灾的地理范围是24°15′-26°54′N,104°-118°E,其中,重灾区是湘南、赣南、桂北和粤北地区,在粤、桂、赣3省区,寒害的垂直分布发生在在海拔300~600 m范围以内.受灾树木断顶、折干、弯曲、倾覆、树皮冻裂或枝叶冻枯,多数植株以遭受机械损害为主,发生生理冻害的情况极少.根据综合受害等级分析,巨赤桉无性系DH201-2受害程度最重,尾巨桉DH32-29和巨尾桉无性系GL9等次之,邓恩桉和巨桉耐寒性较强,受灾程度相对较轻.通过对灾情的调查和分析,提出关于今后桉树人工林发展的建议.  相似文献
3.
我国南方公路劣质地植被恢复方法探讨   总被引:1,自引:0,他引:1  
针对我国南方公路两侧坡陡、土壤干旱瘠薄、立地条件差、造林施工难度大的特点,提出以固坡防蚀,控制泥沙径流为主要目的,兼顾绿化景观层次的植被恢复方法.  相似文献
4.
论中国南方近自然混交林营造   总被引:1,自引:0,他引:1       下载免费PDF全文
德国哥廷根大学木材生物学与木材工艺学研究所所长 Edmone Roffael最近指出 ( 2 0 0 0年 1 1月 1 7日 ) ,木材过去和现在都是一种最重要的天然原材料。许多著名科学家近年来又反复论证 ,认为木材的地位和意义在未来呈上升趋势。他们的根据主要有 3点 :1 .木材生物合成是一个有利于环境的过程 ,减轻环境负担 ,通过光合作用固定太阳能和 CO2 ,把有效能量与熵蓄贮起来。2 .世界许多地区的实践证明 ,通过速生造林与森林的集约经营 ,扩大木材供应潜力的可能性是广泛存在的。速生人工林平均每公顷能年产 2 0m3木材 ,相当于每天可产 1 5g纤维素或…  相似文献
5.
南方高海拔山地引种栽培日本落叶松研究   总被引:1,自引:1,他引:0  
南方高海拔山地因风大,冬季寒冷,雪压严重,选择速生用材造林树种,难度较大。从北方引种日本落叶松(LanxKaempferi(Lamb.)Cars.),通过五年的栽培试验研究,结果表明:日本落叶松具有生长迅速,耐寒、抗风、抗雪压能力特别强,材质优良等特点,适宜作南方高海拔1300m以上地区的速生用材造林树种推广。  相似文献
6.
Calorific value of plants is an important parameter for evalu- ating and indexing material cycles and energy conversion in forest eco- systems. Based on mensuration data of 150 sample sets, we analyzed the calorific value (CV) and ash content (AC) of different parts of Masson pine (Pinus massoniana) trees in southern China using hypothesis testing and regression analysis. CV and AC of different tree parts were almost significantly different (P〈0.05). In descending order, ash-free calorific value (AFCV) ranked as foliage 〉 branch 〉 stem bark 〉 root 〉 stem wood, and AC ranked as foliage 〉 stem bark 〉 root 〉 branch 〉 stem wood. CV and AC of stem wood from the top, middle and lower sections of trees differed significantly. CV increased from the top to the lower sections of the tnmk while AC decreased. Mean gross calorific value (GCV) and AFCV of aboveground parts were significantly higher than those of belowground parts (roots). The mean GCV, AFCV and AC of a whole tree of Masson pine were 21.54 kJ/g, 21.74 kJ/g and 0.90%, re- spectively. CV and AC of different tree parts were, to some extent, cor- related with tree diameter, height and origin.  相似文献
7.
文章在阐述中国南方喀斯特多功能植物园建设意义的基础上,提出了建园的可行性,并就南方喀斯物植物园发展的核心、任务、目标和归宿进行了讨论。  相似文献
8.
We present management tools for growing four valuable broadleaved tree species, indigenous to subtropi.cal southern China. Crown diameter (CD) of the species studied can be predicted very well by using a model that is so e y a near funct on of d ameter at breast he ght (DBH). The add t on of tree age (AGE) and yield class (YC) to this-nodel did not significantly improve its predictive capacity. We used species-specific crown diameter models to calcu- ate the amount of growing space and subsequently stand density that each species needs to achieve desired stem "adial growth rates. Furthermore we used this information to calculate a "distance factor", a rule of thumb that roughly ~stimates the distance between two neighboring trees needed to achieve a desired future target diameter. These tools 'acilitate the planning of thinning regimes by using crown diameter models combined with annual radial growth rates to ;alculate the number of crop trees per hectare required to reach a desired target stem diameter.  相似文献
9.
Shebao Yu  Dan Wang  Wei Dai  Ping Li 《林业研究》2014,25(3):621-626
Understanding the age effect on soil carbon balance in forest ecosystems is important for other material cycles and forest man-agement. In this research we investigated soil organic carbon density, litter production, litter decomposition rate, soil respiration, and soil mi-crobial properties in a chronosequence of four Chinese fir plantations of 7, 16, 23 and 29 years at Dagangshan mountain range, Jiangxi Province, south China. There was a significant increasing trend in litter production with increasing plantation age. Litter decomposition rate and soil respira-tion, however, declined from the 7-year to the 16-year plantation, and then increased after 16 years. This was largely dependent on soil micro-organisms. Soil carbon output was higher than carbon input before 16 years, and total soil carbon stock declined from 35.98 t·ha-1 in the 7-year plantation to 30.12 t·ha-1 in the 16-year plantation. Greater litter produc-tion could not explain the greater soil carbon stock, suggesting that forest growth impacted this microbial process that controlled rates of soil car-bon balance together with litter and soil respiration. The results highlight the importance of the development stage in assessing soil carbon budget and its significance to future management of Chinese fir plantations.  相似文献
10.
This article analyzes the factors shaping commercial timber profit distribution in China's Southern Collective Forest Region (hereinafter SCFR). The article first describes the setting and distribution of a national harvest quota and analyzes its equity impacts on farmer households. Based on access mapping of the commercial timber commodity chain, profit distribution and mechanisms for controlling and maintaining access to profit are analyzed for different actors along the chain. The data show that farmers do not benefit to a great extent from the commerce, even if they are endowed with rights to manage and harvest forests and freely sell commercial timber in the region. There are a number of institutional and non-institutional factors that determine the extent of benefits farmers and other actors along the timber commodity chain can seek. Under current arrangements, the devolution of forest property in the SCFR does not ensure that farmer households benefit from commercial timber marketing. In order to stimulate farmers' enthusiasm for forest rehabilitation and management, beyond the devolution of forest property, it is firstly necessary to take effective measures to improve farmer access to commercial timber profits.  相似文献
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号